Polypeptide analysis with monoclonal antibodies of A type inclusion bodies induced by cowpox virus

Preparation of Monoclonal Antibodies Cross-Reactive with Orthopoxviruses and Their Application for Direct Immunofluorescence Test

Variola virus (smallpox virus), vaccinia virus (VV), cowpox virus (CPV) and ectromelia virus (EV) belong to the genus Orthopoxvirus of the family Poxviridae. To establish the possible diagnosis for smallpox infection, monoclonal antibodies (MAbs) against VV and CPV were produced. The cross-reactivity of seven MAbs with cells infected with various strains of the orthopoxviruses (CPV, VV and EV) was confirmed by an immunofluorescence (IF) test and other immunological analyses. Four and three MAbs reacted with the common antigen of all poxviruses (probably NP antigen) and the antigen involved in neutralization, respectively. We developed the IF test using these MAbs. The direct IF test required only 45 min to perform. Smallpox infection is now eradicated, but it is important to prepare for the diagnosis of smallpox in an emergency. The direct IF assay using MAbs cross-reactive with orthopoxviruses is rapid, simple, specific, applicable for multiple samples, and will make it possible to screen for and detect orthopoxviruses that include variola virus with tissue impression smears from skin lesions in most laboratories or institutes.

Identification and characterization of three immunodominant structural proteins of fowlpox virus

Genes encoding fowlpox virus (FWPV) structural proteins have been identified mainly by sequence homology with those from vaccinia virus (VACV), but little is known about the encoded proteins. Production of monoclonal antibodies (MAbs) against Poxine and HP1-440 (Munich) clone FP9 allowed the identification of three immunodominant FWPV proteins: the 39-kDa core protein (encoded by FPV168, homologous to VACV A4L), a 30- and 35-kDa protein doublet, and an abundant 63-kDa protein. The 30- and 35-kDa proteins are nonglycosylated, antigenically related proteins present in the intracellular mature virus membrane and localizing closely with the viral factories. N-terminal sequencing identified the 35-kDa protein as encoded by FPV140 (the FWPV homolog of VACV H3L). The 63-kDa protein forms covalently linked dimers and oligomers. It remained mainly insoluble upon detergent treatment of purified virus but did not localize closely with the viral factory. N-terminal sequencing was unsuccessful, suggesting N-terminal blocking. CNBr digestion generated a peptide encoded by FPV191, predicted to encode one of two FWPV A-type inclusion (ATI) proteins. The characteristics of the 63-kDa protein were inconsistent with published observations on cowpox or VACV ATI proteins (it appears to be essential). The 63-kDa protein, however, shares characteristics with both VACV p4c virus occlusion and 14-kDa fusion proteins. Gene assignment at the poxvirus ATI locus (between VACV A24R and A28L) is complicated by sequence redundancies and variations, often due to deletions and multiple frameshift mutations. The identity of FPV191 in relation to genes at this locus is discussed.

Heterogeneity of protein profiles of Helicobacter pylori isolated from individual patients

BACKGROUND

In order to characterize the diversity of Helicobacter pylori (H. pylori) in infected individuals, 10 colonies of H. pylori were isolated from the gastric juice of 25 patients with gastroduodenal diseases (total 250 isolates).

METHODS

Protein profiles of isolates were compared by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). Results were confirmed by Western blotting (immunoblotting) test using rabbit antisera against three different strains of H. pylori.

RESULTS

The protein profiles of 18 of 25 cases (72%) showed a single type of H. pylori with the same polypeptide pattern. In contrast, heterogeneity in the protein profiles was seen in isolates from seven cases (28%). Two differing H. pylori types with two very different polypeptide patterns were found in 10 isolates from one case. In six patients, the protein profiles of isolates were found to have variations in their polypeptides between molecular weights of 30,000 (30K) and 14K, which are thought to be associated with bacterial membrane protein. In some isolates, a polypeptide band of the 16K was missing. Each of three different antisera confirmed differences among the distinct isolates from individual patients.

CONCLUSIONS

These findings suggest that more than one antigenically different strain of H. pylori may exist in same infected individuals.

Serum antibody against Helicobacter pylori assayed by a new capture ELISA

We developed a highly specific detection technique for serum antibody, using a monoclonal antibody to a specific antigen of Helicobacter pylori. A monoclonal antibody preparation that reacted with the 54-kDa molecule of H. pylori antigens was obtained. Using this preparation, an antigen-capture enzyme-linked immunosorbent assay (ELISA) was established by fixation of the monoclonal antibody, followed by reaction with sonicated whole cell antigens. The serum antibody titers of patients with gastritis and peptic ulcers were significantly higher than control titers, and the antibody titer correlated with the histological severity of gastritis. Patients positive for H. pylori by bacterial culture had higher titers than H. pylori-negative patients. Our new ELISA may be useful for the diagnosis of H. pylori infections and for evaluation of the severity of gastric inflammation.

Detection of immunoreactive antigen, with a monoclonal antibody to measles virus, in tissue from a patient with Crohn's disease

Using immunofluorescence (IF), we investigated reactive antigens present in Crohn's disease patients with monoclonal antibodies derived from cells infected with measles virus, but not with the subacute sclerosing panencephalitis virus. During immunoblotting, one monoclonal antibody (mAb 86) reacted with a polypeptide with a molecular weight of 36,000 dalton (M; matrix protein) in measles virus-infected cells. This monoclonal antibody displayed a positive reaction only with tissues from patients with Crohn's disease by the IF test. It did not react with samples from patients with other chronic inflammatory bowel diseases, such as ulcerative colitis. Other monoclonal antibodies to the measles virus protein, and monoclonal antibodies to Herpes simplex virus type 1 did not react with the same tissue samples. The role of measles virus infection and/or a viral antigen (possibly the M protein) as a causative agent in Crohn's disease poses a challenging avenue for further research.

Messenger RNAs of a strongly-expressed late gene of cowpox virus contain 5'-terminal poly(A) sequences

We have identified and characterized one of the most strongly-expressed genes of cowpox virus (CPV). This is the gene encoding the major protein component of the A-type inclusion bodies produced by this virus. This gene (designated the 160K gene) is transcribed late during the infection. Analyses of its mRNAs showed that these late RNAs, unlike all other characterized late mRNAs of poxviruses, are uniform in length. However, the most remarkable feature of the mRNAs of the 160K gene is the structure of their 5'-termini. Most of these mRNAs have 5'-terminal poly(A) sequences containing 5-21 residues. Furthermore, these 5'-terminal poly(A) sequences are not complementary to the corresponding region of the template strand of the viral DNA. Instead, the nucleotide sequences of the mRNA and the viral DNA diverge at the site of the three As in the sequence 5'-TAAATG-3' containing the gene's initiation codon. Consequently, the poly(A) provides the leader sequences of these mRNAs. These unusual 5'-terminal structures suggest that the late mRNAs of pox-virus genes are generated by a novel process.

Cross-reactivity among cowpox, ectromelia and vaccinia viruses with monoclonal antibodies recognizing distinct antigenic determinants in A-type inclusion bodies

Several monoclonal antibodies recognizing distinct antigenic determinants in A-type inclusion bodies (ATIB) induced by cowpox virus (CPV) were obtained to examine the cross-reactivity among various strains of poxviridae, comprising CPV, ectromelia virus (EV), vaccinia virus (VV) and Shope fibroma virus (SFV). The monoclonal antibodies were classified into at least 3 groups on the basis of the results of an immunofluorescence test and immunoblotting; i. e., strain-specific, CPV and EV-specific and Orthopoxvirus (CPV, EV and VV)-specific antibodies. Differences were found between the antigenic determinants of ATIB of LB strains (LB red and LB white) and other strains (Amsterdam, 53, 58 and 60) of CPV and also between those of ATIB of CPV and EV. An interesting finding was that VV also produces the antigen analogous to that associated with ATIB in CPV- and EV-infected cells despite the absence of morphologically defined ATIB.